stion 9 of 11 When females choose mates, why might extreme secondary sexual traits in males be good predictors of mate quality? Those males with extreme traits are more aggressive and will defend their territories and their offspring from predators. Males with the most extreme traits tend to be monogamous and help raise their offspring, increasing offspring survival. Only healthy males display secondary sexual traits, so males with the traits may have genes that keep them healthy. Males that survive despite the handicap of an extreme trait may signal that they are healthy and have good genes.